Offset inlet port for supercharging



Jan. 29, 1946 i G. R. NEUMANN EI'AL 2,393,703

' OFFSET INLET PORT FOR SUPERCHARGING Filed' Nov. s, 1943 Patented Jan. 29, 1946 OFFSET INLET PORT FOR SUPERCHARGING George R. Neumann, St. Clair Shores, and Eugene F. Farrell, Grosse Point Woods, Mich., assignors to Borg-Warner Corporation, Chicago, 111., a corporation of Illinois Application November 5, 1943, Serial No. 509,077

1 Claim.

This invention relates to improvements in the charging and scavenging of the firing chamber in the cylinders of engines and the like, and especially two cycle explosive engines such as gasoline engines. The invention is a continuation in part of the subject matter of application Serial No. 509,076 executed and filed of even date herewith.

It is an object of this invention to disclose a novel means of scavengingremoving the burned exhaust gases from the firing chamber in the cylinder of an engine, and then charging the firing chamber with fresh fuel gases. In connection with the above it is a feature of the invention that the fresh explosive gases perform the scavenging operation; that the inlet and exhaust ports of the Cylinder may lie in substantially the same general imaginary cutting plane passed at substantially right angles transversely through the bore of the cylinder; that the exhaust ports be adapted to close upon movement of the piston in one direction before the inlet ports close whereby the cylinder is substantially charged with fresh gas; and that the inlet port have connections to a source for char ing and loading with fuel hereinafter sometimes referred to more specifically as supercharging, whereby such fresh explosive gas is introduced into the cylinder. .By supercharsing' as herein referred-to is also meant charging where accomplished by inlet pressure sufiiciently above that in the cylinder firing chamber to cause the fresh fuel to enter when the inlet port is opened.

It is another particular object of the said invention topresent a detailed construction wherein no valve other than the piston is necessary to close the inlet port for the prevention of backfiring. In this connection it is a feature of the invention that the detailed construction shown in the drawing accomplishes the purpose of scavenging without the necessity of such valves, the fresh gas under pressure providing sumcient inertia at normal speeds of operation, to prevent back-firing past the inlet port.

It is a feature of the invention to make use of a piston which preferably is peculiarly shaped to be what may be termed humped at its top and which performs the closing of the inlet norts and outlet ports in the desired timed relation, and whereby the fresh gases are directed upwardly into the firing chamber in the interior of the cylinder and away from the outlet port. to create a downward or pushing'pressure moving the burned gases toward the outlet ports for the scavenging operation.

Other and more specific objects, advantages and uses of our invention will become more apparent from a reading of the following specification taken in connection with the accompanypanying drawing which forms a part thereof and wherein:

Fig. 1 is a fragmentary, sectional, side elevational view, partial schematic, showing the details of this invention; and

g. 2 is a view taken on the lines 2-2 of Fig. 1 looking in the direction of the arrows.

Referring more in detail to the construction shown in the various figures, there i provided a cylinder A for a twocycle air-cooled gasoline engine having a firing chamber ill in which is fitted for reciprocating action, the humped piston D. ,As shown by dotted lines, this piston is connected by a piston rod to the crank shaft of an engine.

There is also shown what may be described in its entirety as the carburetor B, connected by a conduit to the cylinder A as hereinafter set forth, and likewise connected to a pressure accumulator or other source of high pressure C.

The cylinder A is provided with one or more, preferably a plurality of, inlet ports I2, and one or more outlet or exhaust 'ports l4. These inlet ports and exhaust ports are located preferably in the same general area or plane, in the cylinder wall, but at diametrically opposite positions, said inlet ports and said outlet ports, preferably are of different size, as the inlet port l2 extends a greater distance. toward the upper closed or firing chamber end of the cylinder than the exhaust ports l4. With this arrangement, when the piston D moves upwardly, in the illustration shown, the outlet ports M of the cylinder are closed before the inlet ports I! are closed,-whereby a substantial amount of fresh gas is introduced into the cylinder A for the firing operation. The inlet ports l2 communicate with the inlet manifold 16, and the outlet ports l4 communicate with the exhaust or outlet manifold I 8. In the preferred embodiment shown, four inlet ports, for better distribution of gases and more uniform charging, are shown.

The piston D preferably is provided with a raised or stepped top portion which has the concaved surface 42 located relatively close to the outer periphery of the piston nearest to the inlet ports l2 of the cylinder, whereby gases entering from the inlet ports l2 under pressure are deflected upwardly into the firing chamber IU of cylinder A. The piston likewise preferably has the concaved surface 44 on the side adjacent the outlet ports l4, whereby the exhaust gases exert an outlet pressure forcing them out the ports l4, and assuring their escape from the cylinder. It will be noted that the concaved surface 44 is preferably larger in area and with a longer slope than the concave surface 42, whereby the exhaust gases are more effectively directed to the exhaust ports in the escape of said exhaustgases from the cylinder.

The carburetor B has a carburetor tank or bowl as in which is located means such as a float 48 controlling the amount of fuel in the bowl 36. The fuel conduit 30 connects with a fuel tank (not shown) and the float 48 has a needle valve which registers with the end of the fuel conduit 30 and cuts off the fuel when the depth of the liquid in the bowl 36 reaches a sufficient amount to bring the float 46 t the position shown in Fig. l.

The pressure conduit 26 leads from the pressure accumulator C to the outlet ports l2. There is located, within this conduit 26, the end of a fuel pipe 24 This fuel pipe 24 extends down into the liquid in the bowl 36, and has its discharge end located in the venturiill in the pressure conduit 26.

In order .to place the fuel in thebowl 36 under pressure, the reference tube (herein called pressure pipe") 28 is provided leading from the pressur conduit 26 to a position above the fuel in the bowl 96.

The flow of fuel from the bowl 86 into the venturi is regulated and controlled by the needle valve 34. This needle valve 34 registers with the end of the fuel pump 24, whereby threading the needle 34 outwardly" opens the end of the fuel pipe 24 and causes a greater amount of fuel to flow into the venturi and be picked up by the air pressures passing therethrough. Conversely, the flow of the fuel may be restricted by threading the needle valve 34 inwardly to where it restricts the end of the pipe 24.

The cylinder A may be provided with any convenient firing means, such for example as the spark plug 40.

The operation of the device is as follows:

The accumulator G contains a supply of gas under pressure, preferably air, which pressure is carried by the pressure conduit 26 through the venturi and manifold l6 into the port 12. Likewise, pressure existing in the pressure conduit 26 is directed into the bowl 36 by means of the pipe 28. Fuel from the tank (not shown) flows through the fuel pipe 30 into the bowl 36 until the float is raised to the position (shown in the drawing) where the needle valve carried by the float, closes the end-of the fuel pipe 36. Fuel frombowl 36 is carried through the fuel pipe 24 and discharged into the venturi 20 where it is picked up as vapor by the air or gas pressure in the pressure conduit 26, carried through the inlet manifold and discharged through the ports l2, upon opening of those ports. As the piston moves downwardly," in the embodimentshown, from the firing position under pressure of the flred gases, the port I2 opens and the pressure of the fresh gases in the manifold l6 forces the gases into the firing chamber In of the cylinder A. Upon further downward movement of the piston, the outlet port or ports l4 open allowing the escape of the fired gases under pressure from the supercharged fresh gases. The fresh gases coming through the ports I: are deflected upwardly by the concave surface 42 toward the closed end or firing chamber In of the cylinder A, and the exhaust gases fiow outwardly under the impact of the fresh supercharged gases and under the pressure of the expanded exploded gases themselves, through the ports l4 and are carried oif through the exhaust manifold 16. I

The completeness of exhaustion of the fired gases depends upon the differential in pressure between the ambient air, the burned gases in the chamber, and the pressure in the charging means. Ordinarily, the gases are not all exhausted at sea level due to the ambient pressures, but exhaustion of ,the burned gases increases with the increase in altitude. This automatically tends to regulate the amount of fresh gases introduced into the firing chamber and thus exertsan automatic control on the speed of the engine. This automatic control is desirable because the operation of the engine at higher altitudes will normally be required to be faster than at sea level.

On the upward stroke of the piston D, the exhaust ports I4 are closed. before the inlet ports I2 are closed, whereby substantial supercharged gas for the next firing of the piston is introduced into the cylinder A. After the firing operation the sequence repeats. v

It will be noted that with this arrangement no valve is needed to close the inlet ports l2 until the exhaust gases have been removed from the cylinder.

This arrangement is very advantageous for use with two-cycle engines, and while it may possibly apply to other types of devices and engines, the application to two-cycle engines as shown herein is superior to its application'to such other devices.

While we have described our invention in connection with certain specific embodiments thereof, it is to be understood that this is by way of example and that we intend our invention to be defined by the appended claim.

We claim:

In a device of the class described a cylinder containing a firing chamber, gas inlet and exhaust port in connection with said cylinder, a reciprocating piston in said cylinder, said piston being adapted to open and close said inlet and exhaust port in timed relation, the arrangement being such that said exhaust port is closed before said inlet port, an accumulator, the fluid pressure conduit from said accumulator to said inlet port means, a venturiin said fluid pressure conduit direction from said outlet port means upon entry of said gas into said firing chamber through said inlet port means.

- GEORGE R. NEUMANN.

, EUGENE F. FARRELL. 

